When machining a variety of materials such as metals and composites, lubricating fluid and/or air is generally utilized to facilitate heat transfer and/or chip removal. In the case of relatively small items that may be placed within a milling machine, for example, a stream of fluid or coolant may be delivered to the milling site via a fluid line separately arranged from the cutting tool. However, when forming relatively deep holes and/or when machining relatively large items, for example, with portable milling devices, it may be advantageous to deliver fluid more directly to the tip of the cutter. So called fluid chucks are generally utilized to both hold these cutting tools and provide for fluid delivery. These fluid chucks typically include a fluid coupling and a conduit to deliver coolant to the cutting tool.
A disadvantage associated with some conventional fluid chucks is that the flow of fluid is not regulated in connection with the cutting action and thus, fluid may flow out of the cutting tool while no milling action is being performed. In an attempt to overcome this disadvantage, automatic shutoff valves have been incorporated into fluid chucks. These automatic valves are generally referred to as “inducers” as they are induced to initiate coolant flow in response to contact with a material being machined. However, these known fluid inducers have not fully overcome these disadvantages and, by way of example, are sometimes susceptible to leaking. Also, these inducers occasionally “stick” and fail to shut off the flow of fluid at the completion of a cutting operation. Problems associated with stuck valves include fluid waste and “back side contamination.” The phrase “back side contamination” refers to fluid discharged by the cutting tool after penetration of the material. That is, as the milling tool or drill bit exits through the back of the material, fluid continues to flow and splashes the back side of the material. This problem may be particularly troublesome in the aerospace industry. For example, when machining airframes, back side contamination may foul the interior of the airframe necessitating additional cleaning operations and involving time and money. In addition, there are health concerns associated with cooling fluids. Therefore, back side contamination may have a negative impact on the health of machine operators in the vicinity.
Another disadvantage associated with known fluid chucks having automatic shutoff is that the preload and travel are factory set. The term “preload” refers to an amount of resistance the automatic shutoff mechanism requires to open it for flow, and thus relates to the force required to open the shutoff valve and start the flow of fluid. The term “travel” refers to the degree of movement of the automatic shutoff mechanism required to open the shutoff valve and start the flow of fluid. Optimal preload and travel depend upon a variety of factors such as type and thickness of material machined, diameter of cutting tool, feed rates, and the like. Consequently, the factory settings are usually only optimal for a relatively narrow range of cutting operations.
Yet another disadvantage associated with known inducers is that the preload and travel settings are generally not adjustable and may tend to fluctuate with time and use.
Accordingly, it is desirable to provide a method and apparatus capable of overcoming the disadvantages described herein at least to some extent.